t = [ -1 0 1 2 ]'
y = [1 1 2 3 ]'
einsen = ones(4,1)
A = [ einsen, t ]
Aty = A' * y
AtA = A' * A
x = mldivide( AtA, Aty )
gerade = A * x
plot( t, y , 'o' , t, gerade)